Centrifugal pumps

ABSTRACT

A centrifugal pump for pumping liquid in which pieces of contaminating material may be present; the pump comprising a reservoir chamber, an impeller casing, a rotary impeller mounted to rotate in an annular space within the casing which is formed with at least one inlet to the eye of the impeller and is mounted at least partly within said chamber, and a volute; and the pump being characterized in that a subchamber from which said inlet opens is provided and is formed with an inflow opening which is so dimensioned that it presents a passageway which is at least as restricted to the passage of pieces of contaminating material as are each of the passageways presented by, firstly, the inlet to the eye to the impeller, secondly, the annular space in which the impeller rotates, and, thirdly, the volute and other waterways in the pump.

United States Patent [72] Inventors Harold Philip Sidney Paish;

Harold Lloyd Dagwell; Peter John Anle all 01 53h Southwark Street,London, S.E.1,

England [21] Appl. Nov 807,061 [22] Filed Mar. 13, 1969 [45] PatentedAug. 10, 1971 [32] Priority Mar. 14, 1968 [33] Great Britain [31]12485/68 [54] CEN'I'RIP'UGAL PUMPS 4 Claims, 2 Drawing Figs.

[52] US. Cl 415/98, 415/213, 415/204 [51] lnt.C1 ..1 ..F0ld 25/00, F04d7/00 [501 Field 01 Search 103/104, 1 14; 230/133 C; 415/204, 205, 206,170, 97, 98, 213 A, 219

[56] References Cited UNITED STATES PATENTS 3,296,973 1/1967 Paish et a1103/104 3,279,386 10/1966 Rupp et a1. 103/114 2,430,299 11/1947 Mann103/104 2,278,772 4/1942 Duden 103/104 2,251,807 8/1941 Ruthman 103/1042,143,032 l/1939 Ruthman... [03/104 3,130,679 4/1964 Sence 415/213 A3,190,226 6/1965 Judd 415/213 A FOREIGN PATENTS 1,108,531 10/1955 France103/114 Primary Examiner-Henry F. Raduazo Attorneys-William D. Hall,Elliott l. Pollock, Fred C. Philpitt, George Vande Sande, Charles F.Steininger and Robert R. Priddy ABSTRACT: A centrifugal pump for pumpingliquid in which pieces of contaminating material may be present; thepump comprising a reservoir chamber, an impeller casing, a rotaryimpeller mounted to rotate in an annular space within the casing whichis formed with at least one inlet to the eye of the impeller and ismounted at least partly within said chamber, and

pump.

CENTRIFUGAL PUMPS BACKGROUND OF THE INVENTION This invention relates todouble entry centrifugal pumps for pumping contaminated fluids, e.g.water in which dirt and stones may be present.

One example of this type of pump is sold under our Trade Mark VELOVACand is described in the specification of our British Pat. No. 1,048,272.This prior pump comprises a reservoir chamber in the lower part of whicha pump casing is arranged, and in use water is drawn from the chamberinto a pair of annular inlets to the eye of the rotary impeller whichfeeds to the volute. Although an intake with orifices to restrain solidslarger than the impeller will pass is normally provided for the inflowends of the suction pipes or hoses for use with such pumps, it notinfrequently occurs that the users omit to fit the intakes; it is alsotrue that lengths of pipe and hose for use with the pumps are sometimesstacked in the open and are frequently dragged into position in such amanner that large solids enter the pipes and hoses. Such solids, unlesspreviously removed, immediately enter the pump when it is started.

It should be understood that the fitting of a strainer with smallorifices at the delivery end of the suction pipe or hose is not thesolution as such a strainer very soon becomes choked and has to becleaned, and it is an object of this invention to overcome the abovedisadvantages and to make possible long unattended periods ofsatisfactory operation in pumps of the kind described above.

SUMMARY OF THE INVENTION In accordance with the present invention thereis provided a double-entry centrifugal pump comprising a principal orreservoir chamber, a pump casing, a rotary impeller mounted to rotate inan annular space within the casing which is formed with at least oneinlet to the eye of the impeller and is mounted at least partly withinsaid chamber, and a volute, characterized in that a subchamber fromwhich said inlet opens is provided and is formed with an inflow openingwhich is so dimensioned that it presents a passageway which is at leastas restricted as each of the passageways presented by, firstly, theinlet to the eye to the impeller, secondly, the annular space in whichthe impeller rotates, and, thirdly, the volute and other waterways inthe pump.

Suitably, the impeller comprises blades which are of parallel form, asopposed to the outwardly tapered blades which are usually employed inpumps of this kind.

It will be appreciated that any stones or relatively large pieces ofcontaminating material which might block the inlet to the impeller eyeor a subsequent part of the liquid delivery system or which might damagethe rotary impeller, will be arrested at the aforementioned inflowopening which is preferably of annular form.

It is a further feature of the present invention that one or more easilyremovable plugs are provided at the base of the chamber to allow theoversize solids arrested by the inflow opening to be removed.

Other objects and features of the invention will appear from thefollowing description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing acentrifugal suction pump;and,

FIG. 2 is a partly sectional elevation in the direction of arrow II ofFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, thecentrifugal pump functions as a suction pump to deliver water and isprovided with a continuously running auxiliary vacuum pump P for primingand for removal of air during operation of the centrifugal pump.

The pump, according to the present invention, comprises principalchamber 10 in the lower part of which a pump casin; 11 is arranged. Thepump casing encloses a rotary impeller 12 mounted near the end of ashaft 13 which extends through an opening in chamber wall 14 and througha central inlet 15 in casing part 16. Casing I1 is provided with spacedwalls a which extend radially with respect to the axis of rotation ofthe impeller, and which are disposed closely adjacent the opposing edgesof impeller blades 17 to define an annular space a-a surrounding theaxis of rotation of the impeller, in which space the blades 17 rotate.The impeller with blades 17 are of parallel form, i.e. are of constantdimension (measured in the direction of the axis of the impeller) alongtheir radial lengths. A spring-loaded seal 18 is provided around theshaft I3 where it passes through the chamber wall 14. The shaft isdriven, by means of a suitable motor (not shown) at 19. The pump casingis also provided with spaced walls b which define, between themselvesand the walls 0 of the principal chamber, a pair of subchambers 23disposed respectively on opposite sides of the impeller, and a pair offluid inlets 27 from the principal chamber 10 into the subchambers 23.The pump casing is provided, in addition, with further spaced walls dwhich define a pair of fluid inlets 15, 20 from the subchambers 23 tothe annular space a-a at the eye of the impeller. The inlets 15, 20 tothe eye of the impeller are arranged in part 2l of the pump casing, anda boss 22 on the end of the impeller shaft extends through opening 20.Thus an annular inlet is provided at each side of the impeller 12, theseinlets opening from subchambers 23 in the interior of the principalchamber 10 which is, of course, water filled after priming and duringthe operation of the pump.

A volute 24 surrounds the annular space a-a in the pump casing. Theoutlet from volute 24 extends tangentially upwardly from around the pumpimpeller to open into a reflux box or nonretum valve (not shown) fordelivery of water which is drawn into the pump through an inlet openingindicated at 26 in FIG. 2.

In operation, after priming of the pump, water is drawn in through inletopening 26 to enter the principal chamber I0 and thence throughsubstantially annular openings 27 into subchambers 23; each of theopenings 27 is interrupted by three bolt-socket parts 28 of minimumsize. The water is then drawn in through the inlets 15 and 20 and forcedby the centrifugal action of the impeller 12 into the volute 24 and outthrough a reflux box.

According to the present invention, the width, i.e. axial dimension w,of the annular openings 27 (or of the larger opening if they areunequal) is arranged slightly smaller than the smaller radial width x ofthe impeller inlets l5 and 20, the axial width y of the annular space inwhich the blades 1' rotate, the minimum dimension of the cross sectionof L volute 24 and all other waterways within the pump. As a result ofsuch dimensioning of these various openings, any oversize solids such asstones or even metallic objects such as bolts or studs, whichinadvertently reach the centrifugal pump, will be arrested by therestricted openings 27 and will collect in sump 29 of the chamber 10.

Referring to FIG. 2, two readily removable plugs 30 are provided in thesump 29. Each plug comprises a pair of plates 31 which are drawntogether by a butterfly nut 32 on a stem 33 to sandwich a rubber sealingring 34 and so jam the plug securely at the mouth of opening 35 into thechamber sump 29. These plugs can be withdrawn to allow the sump to becleared of oversize solids.

A further general advantage of the construction described is that plate36 which forms a sidewall of the chamber is readily removable forinspection and servicing of the pump interior and even withdrawal of therotor 12 and part of the pump casing without removal of the suction pipeor hose.

We claim:

1. A double-entry centrifugal impeller pump for contaminated fluids,comprising a principal chamber having a pump casing at least partiallydisposed therein, an impeller having radially extending blades providedwith axially oppossaid pump casing having spaced first walls extendingradially with respect to the axis of rotation of said impeller and,

disposed closely adjacent the opposing edges of the impeller blades todefine an annular space surrounding the axis of rotation of saidimpeller in which space the blades of said impeller rotate, a volutesurrounding said annular space in said pump casing, said pump casinghaving spaced second walls defining between themselves and the walls ofthe principal chamber a pair of subchambers disposed respectively onopposite sides of the eye of the impeller and a pair of first fluidinlets from said principal chamber into said subchambers, said pumpcasing having spaced third walls defining a pair of second fluid inletsfrom said subchambers to said annular space at the eye of said impeller,whereby fluid flows, during operation of said pump, from said principalchamber through said first fluid inlets to said subchambers and thencevia said second fluid inlets to the eye of said impeller and to saidannular space whence it is impelled to said volute; the spacings of saidfirst walls, of said second walls, and of said third walls being suchthat the axial spacing between said second walls and the walls of theprincipal chamber at said firstfluid inlets is no greater than theminimum dimension of each one of said second fluid inlets in a directiontransverse to the direction of fluid flow through said second inlets; isno greater than the minimum axial dimension of said annular space; andis no greater than the minimum cross-sectional dimension of said volute.

2. A pump as claimed in claim 1, wherein said impeller blades are ofparallel form.

3. A pump as claimed in claim 1 in which at least one removable plug isprovided in the walls of said principal chamber to permit removal ofoversize solids.

4. A pump as claimed in claim 1 in which a readily removable plate isprovided in a sidewall of said principal chamber to facilitateinspection and servicing of the pump interior.

1. A double-entry centrifugal impeller pump for contaminated fluids,comprising a principal chamber having a pump casing at least partiallydisposed therein, an impeller having radially extending blades providedwith axially opposing edges and mounted for rotation within said pumpcasing, said pump casing having spaced first walls extending radiallywith respect to the axis of rotation of said impeller and disposedclosely adjacent the opposing edges of the impeller blades to define anannular space surrounding the axis of rotation of said impeller in whichspace the blades of said impeller rotate, a volute surrounding saidannular space in said pump casing, said pump casing having spaced secondwalls defining between themselves and the walls of the principal chambera pair of subchambers disposed respectively on opposite sides of the eyeof the impeller and a pair of first fluid inlets from said principalchamber into said subchambers, said pump casing having spaced thirdwalls defining a pair of second fluid inlets from said subchambers tosaid annular space at the eye of said impeller, whereby fluid flows,during operation of said pump, from said principal chamber through saidfirst fluid inlets to said subchambers and thence via said second fluidinlets to the eye of said impeller and to said annular space whence itis impelled to said volute, the spacings of said first walls, of saidsecond walls, and of said third walls being such that the axial spacingbetween said second walls and the walls of the principal chamber at saidfirst fluid inlets is no greater than the minimum dimension of each oneof said second fluid inlets in a direction transverse to the directionof fluid flow through said second inlets; is no greater than the minimumaxial dimension of said annular space; and is no greater than theminimum cross-sectional dimension of said volute.
 2. A pump as claimedin claim 1, wherein said impeller blades are of parallel form.
 3. A pumpas claimed in claim 1 in which at least one removable plug is providedin the walls of said principal chamber to permit removal of oversizesolids.
 4. A pump as claimed in claim 1 in which a readily removableplate is provided in a sidewall of said principal chamber to facilitateinspection and servicing of the pump interior.